A Comparison of Deterministic and Stochastic Approaches to Solve the Facility Layout Problem with Toxic Releases

Process units are grouped into facilities and the facility concept is extended to include services and control rooms. Two approaches, deterministic and stochastic, proposed by the authors in previous studies are compared in this work. The stochastic approach considers the random effect of meteorological conditions, reported in databases, on the toxic dispersion. A Monte Carlo method is used to estimate the directional risk distribution for a given release scenario. The deterministic approach is based on the worst scenario where the stochastic meteorological condition is reduced to calm conditions. The problem was formulated as a disjunctive nonlinear optimization model, converted in a MINLP and solved with the GAMS package. The results indicate that the deterministic approach provides more conservative layouts indicating the need of including means to regulate and reduce the risk.